Saturday, 28 July 2012

Stop the bleeding: questioning emergency trauma care

When trauma patients arrive at hospital with multiple injuries and haemodynamic instability (significant blood loss, low blood pressure, increased risk of dying), apart from resuscitating them (usually by giving blood and other things like clotting factors) the treatment is summed up by the phrase: “Stop the bleeding”.

“Stopping bleeding” is a biologically plausible mechanism for saving life that I will accept on face value. My question is: do our noble attempts to stop the bleeding actually influence the chance of dying? Looking at previous treatments that have fallen out of favour, I would say not. And the treatments currently in vogue are supported by as little evidence as those they replaced.

Sunday, 22 July 2012

Anti-depressants make me sad

Anti-depressants have been around since the 1950’s, but it wasn’t until SSRIs (Selective Serotonin Reuptake Inhibitors), the first being Prozac, came on the market in the 1980’s that things really took off. The safer profile meant that primary care physicians could start prescribing, and Prozac itself became a blockbuster drug (over $US1 billion in annual sales) and a household name. Others followed and by 2005, anti-depressants were the most prescribed drugs in the USA. For most patients, however, they are no better than placebo. That doesn’t mean that they don’t’ work, they just don’t work any better than placebo.

Friday, 20 July 2012

Prostatectomy: doctors just don’t get it.

The results from the latest randomised trial comparing prostatectomy to non-operative treatment for prostate cancer are all over the news, but what caught my eye was the response from a senior clinician in my country. I will address his comment, and a related comment, below.

The study (here) recruited 731 men less than 75 years of age and found that the overall mortality after 10 years was 47% in the surgical group and 50% in the non-operative group. The difference was not statistically different. If it were, you would have to weigh that benefit against the 88% erectile dysfunction and 17% incontinence rates in the surgical group (2 -3 times higher than the non-operative group).

“The whole problem is selecting the ones which need to be operated on”

Thursday, 19 July 2012

Manual handling techniques and back pain

Walking from the change rooms to the operating theatres, I go past a series of posters using drawings of animals in funny positions, extolling the virtues of manual handling techniques. Lifting with your knees, bending with your hips, twisting with your elbows, or whatever. And when I arrive in the operating rooms, I am regularly fascinated by the addition of yet another ingenious device to move a patient less than one metre from their bed to the operating table. Last week we used something that was basically a fully functioning hovercraft (here).

There are countless well-meaning guidelines (and rules) on how we should be moving objects (like this, and this) but do they help? I lift a lot of heavy things in awkward positions when I am working in the yard, but really only get back pain when I lie on my back for too long. I see Olympic weight lifters putting a fair bit of weight through their back without much back pain, and I know that the biggest predictors of back pain in the workplace are not physical factors (try this, this and this) but things like job satisfaction. What is the evidence that this advice, or these devices, actually work?

Why placebo surgery is ethical, and necessary

The research discussed in my previous post on placebo surgery for Parkinson’s disease sparked a rush of publications debating the ethics of placebo surgery, even before the results were released. One of these articles (here) gives a good overview of the ethics of placebo (sham) surgery controls, using one of the Parkinson’s trials as its case in point. The authors give both sides of the argument, but I disagree with two important points; points that lead them to conclude that placebo surgery is not necessary.

Wednesday, 18 July 2012

Placebo surgery #2: Surgery for Parkinson’s disease

In Parkinson’s disease, there is insufficient dopamine in parts of the brain. This chemical can be replaced in pill form, but with variable effect, and with some side effects. In the 1990’s many clinics were transplanting dopamine-producing cells from embryos into the brains of people with Parkinson’s disease. This procedure involved drilling holes in the skull, through which the cells were inserted. Animal studies showed that the cells could survive, and that the procedure could correct some of the movement disorders.  Open label trials (no placebo) of these transplants in humans showed that patients improved. This is the same evidence base for many operations performed today: a biological mechanism, supportive lab studies, and reports of patients that got better. Enter, the sham.

Sunday, 15 July 2012

Placebo surgery #1: Surgery for angina

I will attempt to write a short note on every clinical study that has compared surgery to a placebo operation (sham surgery). The common thread is that while many patients improve after the real operation, many patients also improve after the sham operation, and in each example the real operation is no more effective than the sham surgery. This shows that when we see patients get better after we treat them, it is not necessarily due to the specific effect of our treatment. We (the doctors and the patients) perceive effectiveness by attributing cause and effect to the association we see. The difference between the perceived effect and the specific (real) effect is the placebo effect.

This study dates from 1959, and relates to a surgical procedure for angina that dates from 20 years before that: internal mammary artery ligation.

Saturday, 14 July 2012

Lessons from history #2: Evidence based blood letting

Objections to evidence based medicine (a scientific approach to medicine) by doctors often sound like this:

“Practicing physicians are unwilling to hold their decisions in abeyance till their therapies received numerical approbation. Further, they are not prepared to discard therapies validated by both tradition and their own experience on account of somebody else's numbers.”

Things have not changed.
These quotes are from the early 1800’s and express the attitude of physicians at that time to studies such as the landmark paper in the American Journal of Medical Sciences from 1836. The article (by PCA Louis) systematically pooled data from many patients and used statistics to look at the effectiveness of blood letting for pneumonia (then standard practice). It found the treatment to be ineffective.*

Wednesday, 11 July 2012

Steroid injections for low back pain

The Cochrane review on injections for low back pain concludes: “There is insufficient evidence to support the use of injection therapy in subacute and chronic low-back pain”. The injections contain corticosteroid (‘steroids’, ‘cortisone’) mixed with local anaesthetic and are injected into the epidural region or the facet joints of the lumbar spine. The injections have been compared to placebo injections and to other treatments and, without going in to all the detail, they basically don’t work.

Saturday, 7 July 2012

Prolotherapy: the illusion of effectiveness

Many of my blogs have a recurring theme: an intervention that sounds great (biologically plausible), has great early results, but on rigorous scientific testing is shown to be ineffective. Prolotherapy does not fit that mould, because I don’t even buy the biological argument in the first place. Prolotherapy involves the injection of irritant solutions in order to strengthen tissues and relieve pain. That makes about as much sense as homeopathy, or being struck on the head to relieve a headache.

Thursday, 5 July 2012

The squeaky joint gets the oil: lubricants for osteoarthritis

Hyaluronic acid (HA) is the lubricant that normally oils your joints. In osteoarthritis of the knee, the joints are stiff and painful, and there is less of this lubricant in the joint. So why not inject HA directly into the joints (viscosupplementation)?  Talk about biological plausibility. To many people, this must be very appealing. We know this because people around the world have paid hundreds of millions of dollars to have this stuff injected into their knees. And yet the latest review of the research concludes that HA injections do not provide any significant benefit and may increase the risk of harm. So how do they conclude that, when so many individual studies show that it works? Because the studies are biased.

Sunday, 1 July 2012

The parachute analogy

“You don’t need a randomised trial to prove that parachutes work” is a common refrain from doctors who believe that their operation works, despite a lack of good scientific evidence from controlled trials. They see it as an argument-stopper, but it is actually an example of argument by analogy, and a poor one at that. And at least one surgeon has been burned by putting the parachute analogy in writing.